SU23488A1 - Single AC / DC converter for arc welding - Google Patents

Description

As is known, when working from three-phase networks, for the most part, motor-generators, consisting of a synchronous or asynchronous motor, driven to a three-phase network and a DC dynamo with a “falling characteristic” characterized by the voltage of the machine drops sharply with increasing current in the arc circuit.

It would be highly desirable to connect the two above-mentioned masks into one, resulting in a radial transducer fed from the side of the contact rings from the three-phase current and from the side of the collector feeding the volt arc. However, such an arrangement for arc welding purposes is unacceptable because it does not allow the voltage on the collector to be adjusted within wide limits, starting from zero.

The present invention relates to a single AC / DC converter for arc welding and has the goal of eliminating the aforementioned disadvantage.

In FIG. 1 shows a schematic of the proposed single core converter; FIG. 2-modifying it.

The converter consists of a three-phase winding located in the slots

rotor and connected with three contact rings with a three-phase network / .; Direct current K-windings with a collector; B, b-working brushes on the collector connected to the electrodes of the volt arc F; a, a - excitation brushes feeding excitation coils A-A and A-A; D, D-windings of the poles of the successive excitation and W-damper winding, used for starting-up.

The operation of the machine is as follows. With the synchronous rotation of the core R on the collector between brushes b, b, the potential difference of direct current appears. The voltage between these brushes b, b (which will be denoted by E in the following) depends on the magnitude of the magnetic flux of the poles produced by the excitation coils A, A and A A. Under the scheme of FIG. 1 there are essentially not four poles, but only two, and the north pole here is formed by pole tips L ,, NZ and the south pole form pole tips Sj, S.

When indicated in FIG. 1 the direction of flow created by these poles, the potential difference between the brushes b, b will be equal to

-6 С (01 + 02),

TR & 01 - the magnetic flux created by the poles - Sj

Phg magnetic flux poles

NS - SS C-constant.

As can be seen from FIG. 1 poles of NZ - 2 have mixed excitation. The coils A, A of these poles are powered by 1 aceto (a, a, and the coils D, D are included in the main current circuit /; the coils D, D form ampere turns directed oppositely to the amp revs created by the coils A, L,

With this excitation system, in the case of a small current / voltage between the brushes b, b, as was said, it will be proportional to the sum of the magnetic fluxes:

Yab + 2

With a large current / demagnetizing amp-turns of coils D, D will be so great that they change the direction of flow 02 to reverse, as a result of which the voltage on the brushes ft, b will decrease to a large extent, since it will now not be proportional to the sum, but magnetic flux difference:

fj eee f, - f

With a very large current /, when the electrodes of the arc F are in contact, the action of the serial coils D, D will be so great that the flow F2, directed in the opposite direction relative to the flow F, will be almost equal to the last, so that the resulting flow 1 - 2 will be almost equal to C In this case, the voltage across the collector E will also fall to 0:

6 Ф, - Фз 0.

Thus, with the design of FIG. 1, a sharply falling voltage characteristic fj is obtained, which is very beneficial for arc welding purposes.

Such a single core converter will drop out of synchronicity, when welding by an arc, does not occur, since the resulting magnetic flux of such a single core converter under these conditions will never go to O, but will only rotate by some angle in either direction depending on the flow change. F.

The voltage between the excitation brushes a, and with different operating modes of this machine will retain a more or less constant value, since this voltage will depend on the magnitude of the flux Φ which during the load will hardly change due to the large magnetic saturation of the poles.

A single core transducer can be turned on. At low voltage at L terminals as an asynchronous motor, the squirrel cage in the pole pieces of W-W-W-W will play the role of the secondary winding.

The modification of the described converter consists, according to the scheme of FIG. 2, in that the three-phase current supplying the converter is supplied to the collector winding of the converter, and the excitation shunt circuit is connected to one main brush & and with an auxiliary brush. The voltage between the brushes a 1l b c. the change in load almost does not change, since it exclusively depends on the value of the flux of the NI-Si poles, which almost does not vary with the load due to the large magnetic saturation of these poles.

The subject matter of the invention.

Claims (2)

1. Single-core AC / DC converter for arc welding, characterized by the use of two groups of inductors, of which one group of NI-Si inductors has shunt excitation powered by auxiliary brushes a, a, and the other group of NZ-Sz inductors has a mixed differential excitation with the supply of one winding by the excitation current of the first group of inductors and of the other winding by the current of the welding circuit, so that the magnetic field of the last inductors changes its direction as the current of the welding circuit increases and In this case, the voltage on the brushes b, b was reduced, and the three-phase current supplying the converter to the special winding R cor (Fig. 1). 2.Varification of the converter according to claim 1, characterized in that the three-phase supply current converter is supplied to the converter's collector winding, and the exciter shunt circuit is connected to one main brush bis by an auxiliary brush a (Fig. 2).